Aggression-causing genes appeared early in animal evolution and have maintained their roles for millions of years and across many species, even though animal aggression today varies widely from territorial fighting to setting up social hierarchies, according to researchers from Iowa State University, Penn State and Grand Valley State University.
If these "mean genes" keep their roles in different animals and in different contexts, then perhaps model organisms -- such as bees and mice -- can provide insights into the biological basis of aggression in all animals, including humans, the researchers said.
"This is one of the first investigations to utilize large datasets consisting of thousands of different genes to ask whether there are shared genes relating to similar forms of behavior across a very wide range of animals," said Amy Toth, assistant professor of ecology, evolution and organismal biology, Iowa State. "Specifically, we looked at aggressive behavior in wasps, bees, fruit flies and mice and found a few genes that are consistently associated with aggression. This suggests that even after hundreds of millions of years of evolution, some genes may retain their ancestral roles in similar forms of behavior, like aggression."
The team investigated the expression of aggression genes in the brains and ovaries of paper wasps -- Polistes metricus. Specifically, they looked at wasps belonging to different castes including dominant colony-founding queens, subordinate colony-founding queens, established queens, dominant workers and subordinate workers. These individuals displayed widely different levels of reproductive dominance and, linked to that, aggressive behavior. The team then compared the wasp results to gene expression data already available in honey bees, fruit flies and mice.
"We found that in wasps, which are primitively social insects, aggression genes control the establishment of an individual's dominance over a group,"
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